Tides/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim is swimming in the ocean at night. He comes up from below the surface, stands in the water and sees a sand castle on the quiet beach. Tim: Moby? Moby pops up from behind the sand castle and waves. Moby: Beep. Tim reads from a typed letter. Tim: Dear Tim and Moby, I heard that the Moon controls the tides. Is that true? From, Jackie. The steady rise and fall of the ocean water levels is called the tide. Tides are caused by the pull of gravity between the earth, moon, and sun. (An animation shows Earth orbiting the sun, as the moon orbits Earth) Tim: As you know, gravity is the force that pulls everything in the universe towards everything else. Even though the moon is much smaller than the sun, the moon's pull has a much more pronounced effect on the earth's oceans because it's closer than the sun. (An illustration on graph paper shows the relative distances between the moon, earth, and sun. The moon is much closer to Earth than the sun is, but the sun is much larger) Tim: On the side of the earth that's facing the moon, the pull of gravity causes oceans to bulge outward. On the other side of the earth, the moon's pull on solid ground causes the oceans to bulge there, too. The earth rotates on its axis, and so this bulge is constantly changing location. An animation shows the earth and moon from space. The ocean surrounding the earth's surface is pulled toward the moon. When the earth is also pulled towards the moon, the ocean on the opposite side of the planet bulges outward too. The earth begins to rotate beneath the ocean. Tim: Where the bulge is bigger, it's high tide. Where the water doesn't bulge, it's low tide. An animation shows high and low water levels along a rocky shore, which represent high and low tides. An inset animation shows that high tide occurs when the point's position on the earth aligns with the bulging ocean and low tide occurs when it does not. Tim: The moon's orbit around the earth also causes tidal changes. Most places get two high tides and two low tides each day. (An animation shows the earth rotating as the moon orbits it. The bulge of water follows the moon) Moby: Beep. Tim: Hey, tides are important, Moby. The energy of rising and falling tides can be used to power machinery and make electricity. (An animation shows water flowing through a hydroelectric generation facility) Moby: Beep. Tim: Well, the ocean is strong and unpredictable, so tidal power isn't easy to harness. But it is a clean energy source that doesn't produce much pollution. (An animation shows enormous ocean waves rising and falling) Moby: Beep. (Moby and Tim look at the sand castle on the beach, which the tide is now washing away) Tim: Hey, looks like the tide's coming in. (Moby covers his mouth in horror. Then he looks up and shakes his fists at the moon and shouts) Moby: Beep, beep, beep! Tim: Uh, it's late. I think we should go. (Tim and Moby begin their walk home. A full moon shines in the sky above them) Moby: Beep! Beep! Tim: The moon is not laughing at you. Moby: Beep. (Moby starts shaking his fists at the moon again) Tim: Moby, stop threatening the moon. Moby: Beep, beep! (He continues shaking his fists and shouting) Tim: Ugh. (leaves Moby to argue with the Moon) Category:BrainPOP Transcripts